烟草BZR基因家族鉴定及表达模式分析OA

[Objective]This study aimed to systematically identify the Brassinazole-resistant(BZR)transcription fac-tor family in tobacco(Nicotiana tabacum L.)and analyze its expression patterns,thereby establishing foundation for fur-ther biological functional investigations into its roles in growth and development of tobacco.[Method]A comprehensive bioinformatics approach was employed to identify BZR gene family members in tobacco,with subsequent analysis en-compassing physicochemical properties,structural features,conserved domains,chromosomal localization,gene struc-ture,phylogenetic relationships,collinearity relationship,promoter cis-acting elements,and regulatory network predic-tions.Additionally,transcriptomic data and real-time quantitative fluorescence PCR were utilized to examine the expres-sion patterns of BZR gene family members across various tissues and under diverse abiotic stress conditions.[Result]A to-tal of 22 BZR family members(designated NtBZR1-NtBZR22)were identified from the tobacco K326 genome.The coded amino acids ranged from 179 to 694,with relative molecular weights between 20388.02 and 77808.5 Da and theoretical isoelectric points spanning 5.12 to 9.44;all were classified as hydrophilic proteins.Phylogenetic analysis of 60 BZRs from tobacco,Arabidopsis thaliana,tomato,maize,rice,and melon resolved them into six major clades,with the 22 NtBZRs in tobacco distributed among clades Ⅰ,Ⅱ,Ⅲ,Ⅳ,and Ⅵ,comprising 7,2,4,4,and 5 members respectively.Ten NtBZRs genes were localized on seven chromosomes,whereas the remaining twelve genes were unanchored.Both phylogenetic and collinearity analysis indicated a closer genetic relationship of tobacco BZR genes with dicotyledonous plants.Six conserved motifs(Motif 1-Motif 6)were identified among the twenty-two NtBZRs proteins;all contained Mo-tif 5 and either Motif 1 or Motif 2,which were associated with the BES1_N domain.Except for NtBZR3 protein,all NtBZRs proteins possessed Motif 1,whereas Motif 4 was exclusive to clade Ⅵ.Secondary structure predictions showed that all of the 22 NtBZRs proteins comprised α-helixes,β-sheets,and random coils,with random coils being the predomi-nant form,followed by α-helixes.NtBZRs proteins within the same clade exhibited high similarity in domain,gene struc-ture,and protein structure.Promoter regions of the 22 NtBZRs genes harbored diverse cis-elements responsive to hor-mones,light,plant development,and environmental stresses.A total of 34 transcription factors and 9 microRNA were predicted to potentially regulate NtBZRs gene expression.Expression pattern analysis revealed that,with the exception of NtBZR7,NtBZR8,NtBZR9,NtBZR10,and NtBZR16 which showed undetectable levels in all examined tissues and stress conditions,the remaining NtBZRs genes were expressed to varying degrees,with most members exhibiting higher rela-tive expression in roots and flowers than in other tissues.Notably,NtBZR14,NtBZR18,and NtBZR22 genes displayed marked expression changes under drought and low temperature stresses.[Conclusion]The 22 BZR family members in to-bacco demonstrate high similarity within phylogenetic clades in terms of gene structure,domain,conserved motifs,and higher-order protein structure.NtBZRs genes exhibit tissue-specific expression patterns during tissue morphogenesis,and NtBZR14,NtBZR18,and NtBZR22 genes are likely to play pivotal regulatory roles in response to abiotic stress.